H. J. L. Struycken was a Dutch otolaryngologist, phonetician, and acoustician. After studying medicine in Groningen, in 1893 he started working at the Voorburg psychiatric hospital near Vught, where he attempted to distinguish psychiatric conditions from neurological speech disorders. His interest in phonetics and acoustics took Struycken to France and Germany, to visit clinics and approach instrument makers who could produce tuning forks for him to use in his clinical research.
Adriaan Daniël Fokker was a prominent Dutch theoretical physicist. He is known in theoretical physics for the Fokker-Planck equation and his work on the theory of relativity. In the years around 1930, however, Fokker also became interested in room acoustics and the tuning of musical instruments. He designed several sound reflectors, which amplify the sound reaching the audience, especially in churches, but his work on musical instrument tuning is what made him more widely known.
Cornelis Zwikker was a Dutch physicist and one of the initiators of the Dutch Sound Foundation. After studying chemistry, mathematics, and physics in Amsterdam, he worked with Philips in Eindhoven until 1929, when he was appointed professor of theoretical and applied physics at the Delft University of Technology. Zwikker was responsible for the acoustic design of many buildings, among them the studios of the Dutch broadcasting organization AVRO.
Jules Antoine Lissajous was a high-school teacher, then held prestigious administrative posts in the education system of various parts of France. He had trained in physics, and defended his dissertation on vibratory phenomena in 1850.
The Watkins Electric Music (WEM) Copicat tape echo creates audible repetitions of sounds by using an endless tape loop. As an electronic effect for rock musicians, it was popular during the 1960s, undergoing a series of modifications in the decades following its creation by Charles Watkins in 1958. It is notable for its successful combination of several distinct areas of audio technology: electronic recording, the use of endless loops, and the use of an intermediate storage medium (tape) to achieve delayed playback.
This Excelsior phonograph is a model based on the Edison phonograph and produced by the Excelsiorwerke Cöln factory in Cologne, Germany, between 1903 and 1906. The original Edison phonograph (invented in 1877 by Thomas Alva Edison) is an iconic piece of historical sound technology that is universally associated with the beginning of sound reproduction in the late nineteenth century. It is based on the direct transfer of the vibration of air, caused by a sound source, onto a writing surface, then its playback. During recording, a stylus cuts a spiraling groove into the cylinder.
The Tefifon is an audio player that uses cartridges containing plastic tape with a vertical arrangement of grooves representing sound. It is a branch of analog audio technology that shares some characteristics with other, better-known devices such as the phonograph or the 8-track tape cartridge. The Tefifon combines these developments in novel ways, introducing features that were lacking in other technologies of the era.